I am a very new Linux(mint17-mate mostly) and in MATE I do the above terminal numlockx install, then i go to the 'Appearance"app and under 'options' the number lock enable is no longer dimi just check to enable number lock or uncheck to disable.But, it took me a while to figure out why the numlock check box was dimmed outno numlockx applet comes up with the bin command , but the numlock check box is live